Many container constructions have been proposed for dispensing separate materials which are not to be mixed until just before or after they are dispensed for various reasons, such as to prevent the materials from solidifying in the container. U.S. Pat. Nos. 3,858,853; 4,029,236; and 4,050,612 are specifically noted as dealing with this problem. The devices described in these patents, however, are either more complex and costly or more difficult to use than might otherwise be desired.